Podcast
Questions and Answers
The disodium salt of EDTA is freely soluble in water.
The disodium salt of EDTA is freely soluble in water.
True (A)
EDTA is a bidentate ligand containing 2 oxygen and 2 nitrogen donor atoms.
EDTA is a bidentate ligand containing 2 oxygen and 2 nitrogen donor atoms.
False (B)
EDTA reacts with metal ions in a 2:1 ratio.
EDTA reacts with metal ions in a 2:1 ratio.
False (B)
EDTA is a selective chelating agent.
EDTA is a selective chelating agent.
The stability of the metal-EDTA complex increases in acidic medium.
The stability of the metal-EDTA complex increases in acidic medium.
Murexide is a metallochromic indicator that forms a colorless complex with metal ions.
Murexide is a metallochromic indicator that forms a colorless complex with metal ions.
Eriochrome Black T (EBT) is a pH-independent metal indicator.
Eriochrome Black T (EBT) is a pH-independent metal indicator.
The stability of the metal-EDTA complex is lower than the metal-indicator complex.
The stability of the metal-EDTA complex is lower than the metal-indicator complex.
The bond between the metal ion and the ligand in a complex is a covalent bond.
The bond between the metal ion and the ligand in a complex is a covalent bond.
Coordination number is always an odd number.
Coordination number is always an odd number.
NH3 is a unidentate ligand.
NH3 is a unidentate ligand.
The higher the valence of the metal ion, the less stable the complex.
The higher the valence of the metal ion, the less stable the complex.
The Lewis acid is the electron donor in a complex.
The Lewis acid is the electron donor in a complex.
Ag+ forms 4 coordinate bonds.
Ag+ forms 4 coordinate bonds.
A bidentate ligand is attached to a metal at three sites.
A bidentate ligand is attached to a metal at three sites.
Polydentate ligands are preferred as titrants due to their ability to form weak complexes.
Polydentate ligands are preferred as titrants due to their ability to form weak complexes.
Chelation is a type of complexation where ligands possess only one donor group.
Chelation is a type of complexation where ligands possess only one donor group.
EDTA is a type of ligand that forms water-insoluble chelates.
EDTA is a type of ligand that forms water-insoluble chelates.
A metal with an incomplete subshell will produce unstable complexes.
A metal with an incomplete subshell will produce unstable complexes.
A large ionic radius of a metal increases the stability of a complex.
A large ionic radius of a metal increases the stability of a complex.
A ligand with a high ionic radius increases the stability of a complex.
A ligand with a high ionic radius increases the stability of a complex.
EDTA is used as a ligand for a limited number of metal ions.
EDTA is used as a ligand for a limited number of metal ions.
Flashcards are hidden until you start studying
Study Notes
EDTA (Ethylene Diamine Tetracetic Acid)
- Symbol: H2y2-
- Disodium salt is freely soluble in water: Na2H2y → 2Na+ + H2y2-
- Hexadentate ligand containing 4 oxygen and 2 nitrogen donor atoms
- Reacts with metal in a 1:1 ratio
- Non-selective chelating agent
Reaction with Metal Ions
- M2+ + H2y2- → My2- + 2H+
- M3+ + H2y2- → My- + 2H+
- M4+ + H2y2- → My + 2H+
Factors Affecting Stability of the Complex
- Metal Factors:
- Type of metal: Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+ are strongest to attract ligands
- Ionic radius: Small ionic radius increases stability
- Electric charge: High electric charge produces stable complexes
- Ligand Factors:
- Basic character (ability of electron donation) increases stability
- Ionic radius: Large ionic radius increases stability
Indicators
- Metal Indicators (metallochromic indicator)
- Form colored complexes with metal ions
- Reversible complexation reaction
- Color of free form is different from complexed form
- Stability of Metal-Indicator complex is lower than Metal-EDTA complex
- Examples of Metal Indicators:
- Murexide (H4In- ↔ H3In2- ↔ H2In3-)
- Free form has different color according to pH of the medium
- Complex form has different color according to the type of metal ion
- Eriochrome Black T (EBT)
- Murexide (H4In- ↔ H3In2- ↔ H2In3-)
Polydentate Ligands
- Bidentate Ligand: Attached to metal at two sites (e.g., ethylene diamine)
- Tridentate Ligand: Attached to metal at three sites (e.g., diethylene triamine)
- Tetradentate Ligand: Attached to metal at four sites (e.g., triethylene tetramine)
- Polydentate ligands are preferred as titrants due to:
- Complexes formed are more stable
- Reaction is complete in one step, leading to a sharp end point
Chelation and Complexometry
- Chelation: Type of complexation where ligands possess two or more donor groups
- Ligands combine with metal to form ring structure compounds called metal chelates
- Metal chelates are usually water-insoluble, except for sequestering agents like EDTA
- Complexometry: Type of quantitative analysis where the compound to be analyzed forms a slightly ionized complex
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
